On the topic of copyright… (im not a lawer)
It really depends on your level of profession. If you are a professional animator, you can’t very well claim this is an educational exercise - you’d be expected to create your own charicter to play with…
If you claim you are using the copyrighted charicters for educational (i.e. trying to learn the application) purposes, then you might be protected.
If you are a student in the field, then you are protected almost exclusively, as far as I know … though i am not sure how that would work outside of classroom assignments.
Last, you can make Pinky and the Brain cartoons all you want, so long that you do not distribute the work, and display it only in private showings (i.e., friends and family), and so long as you don’t get a third party in on it (i.e. the equivalent of using Wal-Mart’s photomat to make copies of your family portraits).
If you’re serious about doing multimedia work, make sure to read up on copyright law. The photography and music industries have done a real good job of mucking up our knowlege about fair use.
As far as i know, you can have stacks of copied CD’s in your bedroom closet, so long as you own the original and they never leave your posession. Distribution, I think anyway, is the issue.